From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Performance graph showing the effect of swan neck diameter on a 20/25 HP resonance silencer.
| Identifier | ExFiles\Box 179b\2\ img026 | |
| Date | 12th October 1932 guessed | |
| 20/25 H.P. RESONANCE SILENCER - EFFECT OF SWAN NECK DIAMETER II ① SMALL DIA SWAN NECK - 1.50" ② LARGE DIA SWAN NECK - 2.00" ③ NO SWAN NECK B.H.P. R.P.M. EXHAUST BACK PRESS. (INS. HG) B.M.E.P. | ||